JP2005136521A - Wireless communication apparatus and antenna characteristic improvement method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication apparatus with excellent antenna characteristics even when the antenna is downsized, and also to provide an antenna gain improvement method with a high degree of design freedom. <P>SOLUTION: The wireless communication apparatus 10 accommodates, in its housing 11: a board including a circuit section for wireless communication, a ground conductor 50 for a potential reference and a feeder 18 for interconnecting the circuit section and an antenna 16; and the antenna 16 connected to the feeder 18 on the board and formed by providing an antenna conductor 16b to a base 16a. An auxiliary conductor 17 independent of the antenna conductor 16b is provided to part of the inside of the housing 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication apparatus such as a mobile phone equipped with an antenna for assisting a main function in order to add an auxiliary wireless communication function such as GPS and wireless LAN, and a method for improving characteristics of the mounted antenna. .

  In recent years, mobile units such as mobile phones and wireless communication devices have been rapidly reduced in size, weight, and functionality, and the antenna, which is one of the component parts, has also been reduced in size and weight. A response has been made.

  Under these circumstances, chip antennas using dielectric materials and magnetic materials have been developed. However, there is a problem in that the antenna volume is reduced and the antenna gain is deteriorated due to the miniaturization of the antenna. It was happening.

  In general, in order to secure a gain necessary for communication, it is necessary to optimize the arrangement of the antenna on the mounting board and the layout of other components placed around the antenna. This is because, unlike other mounting parts, the antenna is easily affected by the surrounding environment. In addition to the communication function that is the main purpose, regarding the communication function that is additionally given or the auxiliary communication function of the main function, it is rarely considered even at the mounting position and space of the antenna. It is necessary to mount an antenna in the space and obtain the necessary gain in that state.

  Therefore, Patent Document 1 has developed an antenna having a structure in which a sheet metal is connected as an additional conductor to the radiation electrode of a miniaturized chip antenna to increase the electrical volume.

  FIG. 10 is a transparent perspective view of an antenna device 121 using an antenna having a structure in which a flat additional conductor 125 is connected to the radiation electrode 122 of the chip antenna 126 disclosed in Patent Document 1. FIG.

  In Patent Document 1, in order to achieve the purpose of gain improvement, in a chip antenna 126 in which a radiation electrode 122 is formed on a base 123, a flat additional conductor 125 having one end connected to a part of the radiation electrode 122 and The power supply point 124 for supplying power to the radiation electrode 122 is mounted on the mounting substrate 127. In the present invention, the antenna length can be secured and the resonant frequency of the antenna can be lowered by the effect of shortening the wavelength of the dielectric and the effect of connecting the additional conductor. Further, in antenna characteristics, it is said that the radiation characteristics of the antenna are increased without changing the size of the chip antenna.

  FIG. 11 is a perspective view of an antenna device 141 that uses an antenna in which an annular additional conductor 142 having an electrode removal portion 142a formed at the center portion is connected to a chip antenna 146, which is disclosed in Patent Document 2. is there.

  In Patent Document 2, antenna characteristics can be improved by connecting an additional conductor 142 functioning as a radiation electrode to a base 144 to a chip antenna 146. However, the additional conductor 142 is regarded as a ground, for example, a mounting substrate 147 In reality, it is considered difficult to improve the antenna characteristics because it has unnecessary capacitance with the electronic component 148. On the other hand, when the additional conductor 142 having the electrode removal portion 142a formed at the center is connected, the unnecessary capacitance between the grounds can be remarkably reduced, thereby improving the characteristics of the antenna. Yes.

  Further, FIG. 12 is a perspective view of the antenna device 161 disclosed in Patent Document 3.

In Patent Document 3, the mounting substrate 165 has a shield case 164, and in order to prevent problems with the additional conductor 163, the additional conductor 163 is installed on the side surface side of the base of the chip antenna 162, and the mounting substrate 165. It is said that it is possible to prevent the antenna characteristics from deteriorating by arranging them in a state of being spaced apart from each other by increasing the size of the housing by extending the housing from the mounting substrate 165 and making the housing larger. ing.
JP 2001-339226 A JP 2003-1224736 A JP 2001-358517 A

  Generally, in order to obtain the antenna gain necessary for communication, it is necessary to consider the arrangement and size of the antenna. If the characteristics required for communication cannot be obtained, the layout changes, the antenna size changes, or the case is reached. The problem arises that the previous design must be redone.

  In the conventional antenna device 121 shown in FIG. 10, when the characteristics are to be improved, since the additional conductor 125 is a flat plate shape, a certain area is required, and the antenna is apparently enlarged, and the antenna mounting is performed. Therefore, a substantial space is required, and the effect of downsizing using a dielectric is reduced.

  In the first place, the advantage of chip antennas using dielectric materials is that the radiation wavelength is reduced to 1 / √εr (εr: relative dielectric constant of the dielectric) using the dielectric wavelength shortening effect, and the chip antenna is downsized. It is in. Connecting the additional conductor to improve the antenna characteristics is contrary to the miniaturization of the chip antenna, and increases the size of the chip antenna, which is contrary to the miniaturization effect.

  Further, since the mounting board 127 is regarded as the ground, in this antenna, the larger the additional conductor 125, the more unnecessary capacitance increases between the metal plate of the additional conductor 125 and the mounting board 127. As a result, there is a problem that the antenna gain tends to deteriorate.

  On the other hand, in the conventional antenna device 141 shown in FIG. 11, the electrode removal part 142a is formed in the center part of the additional conductor 142, and the structure which reduced the area of the radiation electrode is provided, and a ground surface is provided. However, the unnecessary antenna capacity is reduced, and the antenna characteristics are stabilized. However, the apparent antenna area in the outer dimensions is increased, and the effect of downsizing using the dielectric is reduced.

  Further, by using the additional conductor 142 from which the central portion is removed, the substantial area as the antenna is reduced, and the electrical volume is reduced, so that there is a problem that the gain is lowered.

  In addition, in the conventional antenna device 161 shown in FIG. 12, the arrangement method of the additional conductor 163 when the shield case 164 is provided is described, but by installing the additional conductor 163 next to the chip antenna 162, Although the unnecessary capacity between the shield case 164 and the additional conductor 163 decreases, an unnecessary capacity is generated between the radiation electrode on the side surface of the chip antenna 162 and the additional conductor 163, and the antenna characteristics are deteriorated. Furthermore, since it is disposed so as to protrude from the mounting substrate 165, an extra space is required, which causes a problem that the housing becomes large.

  In either method, the added conductor is connected to the radiating conductor of the antenna, and the electrical connection at the connection point is inferior in reliability. In order to maintain the posture of the added conductor, it is necessary to take some joining means, which causes a problem that the number of manufacturing steps increases.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a wireless communication apparatus that has a high degree of freedom in design and that has a high gain even if the antenna is downsized. It is an object of the present invention to provide a simpler and improved antenna gain method.

  The wireless communication device of the present invention is connected to a power supply line on the substrate, a circuit unit capable of wireless communication, a ground conductor for potential reference, and a power supply line for connecting the circuit unit and the antenna. A wireless communication apparatus in which an antenna formed by forming an antenna conductor on a base is housed in a housing, wherein an auxiliary conductor independent of the antenna conductor is provided on a part of the inside of the housing. .

  In the wireless communication apparatus of the present invention, the ratio between the maximum value and the minimum value of the electromagnetic field intensity in the vicinity of the casing is 0.8 or more.

  Furthermore, the wireless communication apparatus of the present invention is characterized in that the auxiliary conductor is formed in a part or all of a region except for the upper surface side of the antenna in the housing.

  Furthermore, the wireless communication device of the present invention is characterized in that the thickness of the auxiliary conductor is equal to or greater than the skin depth of a desired frequency.

  The wireless communication device of the present invention is characterized in that the auxiliary conductor is connected to a ground conductor.

  A method for improving antenna characteristics of a wireless communication apparatus according to the present invention includes a circuit unit capable of wireless communication, a ground conductor for potential reference, and a power supply line for connecting the circuit unit and the antenna, and the substrate. A method for improving antenna gain of a wireless communication device in which an antenna having an antenna conductor formed on a base is connected to an upper feeder line, and an electromagnetic field intensity distribution in the vicinity of the housing is measured in advance. In addition, an auxiliary conductor independent from the antenna conductor is provided inside the housing so as to cover a part or all of the region corresponding to less than 90% with respect to the maximum value of the obtained electromagnetic field strength.

  A wireless communication device according to the present invention includes a substrate having a circuit unit capable of wireless communication and having a ground conductor layer, and an antenna connected via a feed line formed in the circuit unit on the substrate in a housing. The wireless communication device accommodated includes an independent auxiliary conductor that is not connected to the antenna in a part of the inside of the housing, so that the antenna gain can be improved without changing the layout of the mounting board. It is possible to obtain a wireless communication apparatus that can perform the communication and has an antenna gain necessary for communication.

  In the wireless communication device of the present invention, since the ratio of the maximum value and the minimum value of the electromagnetic field strength near the housing is 0.8 or more, the radiation resistance near the housing is matched to the radio wave impedance. Thus, the antenna gain can be improved, and a wireless communication apparatus having an antenna gain necessary for communication can be obtained. Further, the electromagnetic wave reaching far is a composite wave of a traveling wave and a reflected wave, and these phase differences can be adjusted to a phase that increases the electromagnetic field strength, and a high gain can be obtained.

  Further, in the wireless communication device of the present invention, since the auxiliary conductor is formed in a part or all of the region except for the upper surface side of the antenna in the housing, the antenna gain is deteriorated without disturbing the radiation from the antenna. Thus, a radio communication apparatus having an antenna gain necessary for communication can be obtained.

  Furthermore, since the thickness of the auxiliary conductor is equal to or greater than the skin depth of a desired frequency, the wireless communication device of the present invention can stabilize the state of reflection of electromagnetic waves in the vicinity of the housing, and thus gain. Improvement is expected.

  In addition, since the auxiliary conductor is connected to the ground conductor in the wireless communication device of the present invention, the resonance frequency unique to the wireless communication device can be adjusted in addition to the above effect. The antenna gain can be further improved by bringing the distance close to, and a wireless communication apparatus having an antenna gain necessary for communication can be obtained. Furthermore, depending on the degree of adjustment, it can also contribute to an improvement in bandwidth.

  A method for improving antenna characteristics of a wireless communication apparatus according to the present invention includes a circuit unit capable of wireless communication, a ground conductor for potential reference, and a power supply line for connecting the circuit unit and the antenna, and the substrate. A method for improving antenna gain of a wireless communication device in which an antenna having an antenna conductor formed on a base is connected to an upper feeder line, and an electromagnetic field intensity distribution in the vicinity of the housing is measured in advance. In addition, since the auxiliary conductor independent from the antenna conductor is provided inside the housing so as to cover a part or all of the region corresponding to less than 90% with respect to the maximum value of the obtained electromagnetic field strength, Since only the auxiliary conductor is added, the antenna gain can be improved without changing the layout of the mounting board, and the auxiliary conductor is not connected to the antenna conductor. Without degrading the reliability of the antenna itself, the antenna gain without taking measures need posture holding the auxiliary conductors can be improved.

  As described above, according to the present invention, it is possible to obtain a wireless communication apparatus having good antenna characteristics even if the antenna is downsized, and to provide a simple antenna gain improvement method that does not deteriorate reliability.

  The best mode of the wireless communication apparatus of the present invention will be described below with reference to the drawings.

  1 and 2 are diagrams showing a first embodiment of a wireless communication apparatus according to the present invention. FIG. 1 is a perspective view, and FIG. 2 is an exploded view of a part of a housing having a display unit in FIG. It is a perspective view.

  As shown in FIG. 1, the wireless communication device 10 of the present invention is, for example, a mobile phone or the like that can be folded freely by connecting a housing 11 having a display unit 14 and another housing 12 by a hinge unit 13. Thus, an external antenna 19 for performing wireless communication is attached to the housing 12 in a structure that can be stored in the housing 12.

  As shown in FIG. 2, a circuit unit (not shown) capable of wireless communication, a ground conductor 50 for potential reference, and the circuit unit and the antenna 16 are connected in the housing 11 having the display unit 14. An antenna formed by forming an antenna conductor 16b in a predetermined pattern on a base 16a made of a dielectric material or a magnetic material, connected to a power supply line 18 on the substrate 15 and a substrate 15 having a power supply line 18 for the same. 16 is housed.

  The antenna 16 functions as an antenna provided to add an auxiliary wireless communication function such as GPS or wireless LAN, or an antenna for assisting a main function, such as a diversity antenna.

  In the wireless communication device 10 of the present invention, it is important to provide the auxiliary conductor 17 independent of the antenna conductor 16b formed on the antenna 16 inside the casings 11 and 12.

  For example, as shown in FIG. 2, a substrate accommodated in the casing 11 is formed by forming an auxiliary conductor 17 inside the casing 11 a on the side close to the antenna 16 of the casing 11 storing the antenna 16. 15 and an antenna gain can be improved without changing the layout of a substrate (not shown) accommodated in the housing 12 and the like, and a radio communication device having an antenna gain necessary for communication can be easily obtained. it can.

  Specifically, when the auxiliary conductor 17 is placed on the transmission line as a load in the space, the effect of matching with the radio wave impedance and the state of reflection of the traveling wave change by the auxiliary conductor 17, and as a result It is considered that the electromagnetic field intensity was able to be increased uniformly and increased because the phases of the wave and the reflected wave changed to be higher with each other. Because of these synergistic effects, the antenna gain is improved, so that a wireless communication apparatus having an antenna gain necessary for communication can be obtained even if the antenna 16 is downsized.

  Moreover, it is preferable that the ratio between the maximum value and the minimum value of the electromagnetic field intensity on a predetermined surface in the vicinity of the casings 11 and 12 is 0.8 or more.

  As a result, the electromagnetic field intensity distribution in the vicinity of the casings 11 and 12 is made uniform, and reflection due to impedance mismatching is less likely to occur over the entire vicinity of the casings 11 and 12, thereby improving the antenna characteristics. When the ratio between the maximum value and the minimum value of the electromagnetic field strength is less than 0.8, there is an impedance mismatch point in the vicinity of the casings 11 and 12, and loss due to reflection tends to occur.

  In addition, the electromagnetic field strength on a predetermined surface in the vicinity of the housings 11 and 12 refers to only the electromagnetic field strength on the main surface side of the housing 11a, for example, as shown in FIG. The value of the electromagnetic field intensity on one side of the side surfaces is shown.

  In addition, in order to make the ratio of the maximum value and the minimum value of the electromagnetic field strength to 0.8 or more in this way, the auxiliary conductor 17 can be formed in the casings 11 and 12. As will be described in detail later, the position where the auxiliary conductor 17 is provided is obtained by measuring the electromagnetic field strength in the vicinity of the casings 11 and 12 before the auxiliary conductor 17 is provided, and in the region where the electromagnetic field strength is low. It can be obtained by providing the auxiliary conductor 17 so as to cover a part or all of it.

  The auxiliary conductor 17 may be any conductive material such as conductive paint, copper tape, etc. Especially, there is little conductor loss, and various forms are used in the form of conductive paint in production. Silver, copper, and gold which can respond to a process are preferable. Further, the auxiliary conductor 17 can be provided by various methods such as manual attachment, spray coating, and brush coating, and the optimum one is appropriately selected according to the form of the conductive material described above.

  Here, a method for determining a position including the auxiliary conductor 17 will be described.

  First, for example, as shown in FIG. 3, before the auxiliary conductor 17 is provided in the housing 11a facing the antenna 16, the electromagnetic field intensity in a region 20 that protrudes about 1 to 2 mm from the outer periphery of the housing 11a. Is measured with an electromagnetic field intensity detection probe at a pitch of 2 to 5 mm and a height of about 1 to 2 mm from the housing 11a.

  At that time, a signal having a desired frequency is input to the antenna 16 through the feed line 18 using a spectrum analyzer. For example, in the case of an antenna having a GPS reception function, the frequency to be input is set in accordance with the application, such as 1.57542 GHz. At each measurement point, the electromagnetic field strength in four directions or more is measured, and the maximum value is taken as the electromagnetic field strength at the measurement point.

  In addition, the state of the wireless communication device at the time of measurement is performed in a state where it is desired to improve the gain. For example, if the gain is improved in the open state, the measurement is performed in the open state, and if the purpose is to improve the gain in the closed state, the electromagnetic field strength in the closed state is measured.

  An example of the electromagnetic field intensity distribution chart thus obtained is shown in FIG. In this embodiment, a state in which a foldable wireless communication device is opened and a state in which an external antenna 19 provided outside is extended are taken as an example. In the electromagnetic field intensity distribution diagram of FIG. 4A, the darker the region, the lower the electromagnetic field strength. The ratio of the maximum value and the minimum value of the electromagnetic field strength at this time was 0.7.

  Next, the auxiliary conductor 17 is formed on the main surface and / or side surface inside the housing 11a so as to cover part or all of the region of about 85% or less with respect to the maximum value of the electromagnetic field intensity distribution.

  Thereafter, the electromagnetic field strength after the auxiliary conductor 17 is provided is measured in the same manner as described above. An example of the result is shown in FIG. The electromagnetic field intensity distribution at this time is smaller in dark portions with lower electromagnetic field strength than in FIG. 4A, the distribution is more uniform, and the maximum and minimum values of the electromagnetic field intensity. The ratio of the values is improved to 0.8 or more, and as a result, it is confirmed that the electromagnetic field strength is increased in the region where the electromagnetic field strength is low before the auxiliary conductor 17 is provided. it can.

  In addition, the auxiliary conductor 17 is formed so as to substantially cover all or a part of the low electromagnetic field strength area, and then the antenna gain is measured. If the auxiliary conductor 17 is insufficient, the area where the auxiliary conductor 17 is provided is finely adjusted. And finally get the required antenna gain. For this reason, only a part of the region having a low electromagnetic field strength, or the entire region, or even a region having a low electromagnetic field intensity may protrude.

  In the above-described measurement of the electromagnetic field strength, only the main surface side of the housing 11a was measured. However, the areas for measuring the electromagnetic field strength are the main surface sides of the housings 11a and 11b and the main surfaces of the housing 12. It is preferable to measure four surfaces from the surface side. In this case, the auxiliary conductor 17 is formed in a region where the electromagnetic field intensity is low in either or both of the housings 11 and 12.

  When measuring only one main surface side of the casings 11 and 12, the casing 11a on the side facing the antenna 16 is measured as described above, and the auxiliary conductor 17 is formed inside the casing 11a. It is preferable to do. This is because the casing 11a is closest to the antenna 16 and has a great influence on the variation in electromagnetic field intensity.

  Further, the auxiliary conductor 17 is preferably provided in a region excluding the outer peripheral surface side and the upper surface side of the antenna 16 in the housing 11.

  For example, when the antenna 16 is accommodated on the housing 11 side and the auxiliary conductor 17 is formed inside the housing 11a, the antenna 16 is mounted on the end of the substrate 15 as shown in FIGS. In this case, the auxiliary conductor 17 is formed in all or a part of the region having a low electromagnetic field strength among the regions indicated by the points in the figure, and is mounted on the center of the substrate 15 as shown in FIG. In such a case, it is preferable to form the auxiliary conductor 17 in a region where the electromagnetic field strength is uniform in the region indicated by the dots.

  This is because if the auxiliary conductor 17 is provided on the outer peripheral surface side and the upper surface side of the antenna 16, radiation from the antenna 16 is hindered, and there is a high possibility that a problem that the antenna gain is reduced occurs. . In particular, in order to avoid interference with radiation from the antenna 16, it is preferable to provide the auxiliary conductor 17 at a position about 3 to 5 mm away from the outer peripheral surface and the upper surface of the antenna 16.

  In addition, the outer peripheral surface side of the antenna 16 in the housing 11 is the surface side where the distance from the antenna 16 is short, that is, in the case of FIG. 5A, the distance from the antenna 16 is short in the side surface of the housing 11a. And the upper surface side of the antenna 16 refers to a surface corresponding to the inner side of the housing 11 a facing the upper surface of the antenna 16.

  Moreover, it is preferable that the thickness of the auxiliary conductor 17 is more than the skin depth of a desired frequency.

  The skin depth δs is a physical quantity determined by the angular frequency ω, the magnetic permeability μ of the conductor, and the conductivity σ, and is expressed by the following equation.

δs = √ (2 / (ω · μ · σ)) [m]
In the microwave band, electromagnetic waves propagate on the pole surface, are attenuated at the skin depth in the depth direction of the conductor, and hardly propagate inside the conductor. However, if the thickness of the auxiliary conductor 17 to be provided is thinner than the skin depth, the electromagnetic wave attenuated inside the auxiliary conductor 17 becomes unstable, making it difficult to obtain stable characteristics. It is preferable that it is more than the skin depth of the frequency. The upper limit is not particularly defined, but when using a paste-like paint or the like, about 0.3 mm or less is preferable from the viewpoint of film strength, and when using a tape-like conductor, 0.5 mm from the viewpoint of work. The following degree is preferable.

  Further, the auxiliary conductor 17 may be connected to the ground conductor 50.

  The wireless communication device 10 has a specific resonance frequency depending on the size of the device itself, mainly the size of the ground conductor 50. By connecting the auxiliary conductor 17 to the ground conductor 50, the size of the ground conductor 50 changes, and accordingly, the inherent resonance frequency of the wireless communication device itself can be changed. By adjusting this to a desired frequency, the antenna gain can be further improved. In addition, depending on how to adapt to a desired frequency, it is possible to adjust the frequency bandwidth capable of communication. The gain can be improved when the resonance frequency after connection with the ground conductor 50 approaches the frequency of the antenna, but it is not improved in all cases. First, connection to the ground conductor 50 is performed for each of various wireless communication devices.

  Next, a second embodiment of the wireless communication apparatus of the present invention will be described with reference to FIGS.

  FIG. 6 is a perspective view showing a second embodiment of the wireless communication apparatus of the present invention, and FIG. 7 is an exploded perspective view thereof.

  As shown in FIG. 6, the wireless communication device 40 has a structure in which a housing 21 having a display unit 24 and another housing 22 are connected by a hinge portion 23 and can be folded freely, as in the above-described embodiment. is there. An external antenna 29 for performing wireless communication is attached to the housing 22 in a structure that can be stored in the housing 22.

  As shown in FIG. 7A, the housing 21 having the display unit 24 accommodates the substrate 25a on which the display unit 24 is mounted and provided with the ground conductor 60a, and the other substrates 22 are accommodated. 25b is connected with a connector or the like. Further, as shown in FIG. 7B, an antenna 26 for performing wireless communication is mounted in the other casing 22 and a substrate 25b provided with a ground conductor 60b is accommodated. Via a line 28, it is connected to a radio circuit unit (not shown) provided on a substrate accommodated in the housing 22.

An auxiliary conductor 27 independent of the antenna conductor 26b is provided inside the housing 21a that accommodates the substrate 25a including the display unit 24.

  Here, according to the wireless communication device 40 of the present invention, the auxiliary conductor 27 independent of the antenna conductor 26b is provided inside the casing 21. Similarly to the first embodiment, since the auxiliary conductor 27 for improving the antenna gain is formed inside the housing 21a, the layout of the substrate 25a accommodated in the housing 21 and the substrate 25b accommodated in the housing 22 is determined. The antenna gain can be improved without changing, and a wireless communication apparatus having an antenna gain necessary for communication can be obtained.

  Also in this case, as in the first embodiment, in order to obtain a more effective effect, the electromagnetic field strength in the vicinity of the housing 21 before the auxiliary conductor 27 is measured, and a region with a low electromagnetic field strength in the region is measured. It is preferable to provide the auxiliary conductor 27 so as to cover it.

  First, as shown in FIGS. 8A and 8B, the electromagnetic field strength in a range 30 protruding from about 1 to 2 mm on the outer periphery of the casing 21 before providing the auxiliary conductor 27 is set at a pitch of 2 to 5 mm. Measurement is performed using an electromagnetic field intensity detection probe at a height of about 2 mm from 21a. At that time, a signal having a desired frequency is input to the antenna 26 through a feed line 28 using a spectrum analyzer. For example, in the case of GPS, the frequency to be input is set according to the application, such as 1.57542 GHz. At each measurement point, the electromagnetic field strength in four directions or more is measured, and the maximum value is taken as the electromagnetic field strength at the measurement point.

  An example of the electromagnetic field intensity distribution thus obtained is shown in FIG. 9A, and the darker area is the area with lower electromagnetic field intensity. The ratio of the maximum value and the minimum value of the electromagnetic field strength at this time was 0.75.

  Next, the auxiliary conductor 27 is provided on the inner side surface and / or upper surface of the housing 21a so as to cover a part or all of the region of about 90% or less with respect to the maximum value of the electromagnetic field intensity distribution. The electromagnetic field intensity after providing the auxiliary conductor 27 is measured in the same manner as before.

  An example of the result is shown in FIG. At this time, the ratio between the maximum value and the minimum value of the electromagnetic field strength is improved to 0.85. As a result, the region where the electromagnetic field strength is low before the auxiliary conductor 27 is provided is It can be confirmed that the strength is high.

  In the second embodiment, the auxiliary conductor 27 is formed not inside the housing 22 that houses the antenna 26 but inside the housing 21a. Even in this case, the electromagnetic field intensity is made uniform as in the first embodiment. Similar effects can be obtained.

  Note that the wireless communication device and the antenna characteristic improvement method thereof according to the present invention are not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention.

  For example, in the case of a mobile phone or the like, it is not limited to a foldable wireless communication device, and may be of a straight shape.

  In the above embodiment, the antennas 16 and 26 having additional functions such as GPS, wireless LAN, and Bluetooth function accommodated in the casings 11 and 22 or auxiliary functions of the main function have been described. , 29, the same effect can be obtained. Therefore, the shape and type of the antenna are not limited at all. In this case as well, the frequency corresponding to the external antennas 19 and 29 is input, and the auxiliary conductors 7 and 22 are placed inside the casings 11, 12, 21, and 22. 27 is formed.

  Furthermore, in the above embodiment, a dielectric material is used as the bases 16a and 26a constituting the antennas 16 and 26. However, a magnetic material can be used, and even air can be used. In this case, the conductor has a predetermined shape. Made up of. However, it is preferable to use ceramics from the viewpoint of miniaturization and ensuring reliability during mounting.

  The position and shape for forming the ground conductor are not limited to the shape shown in the embodiment, and any shape can be adopted in consideration of other components.

  In addition, when improving the gain of an antenna having an additional function or an auxiliary antenna, the antenna having the main function may be in any state, for example, the antenna having the main function is a whip antenna and a telephone function If the objective is to improve the gain when the whip antenna is extended, the auxiliary conductor is designed to increase the electromagnetic field strength in that state. May be provided.

  Next, examples of the present invention will be described.

  A surface-mounted chip antenna was attached to the wireless communication apparatus as shown in the first embodiment, and a 1.575 GHz band wireless communication apparatus for GPS was manufactured.

  As shown in FIG. 2, as a surface-mounted chip type antenna 16, a base body 16a is made of alumina, the dimensions are 10 × 4 × 3 mm, and an antenna conductor 16b made of silver is formed on the surface of the base body. The antenna 16 was accommodated in the housing 11.

  First, the antenna characteristics of this wireless communication apparatus were measured with a network analyzer for the center frequency and band, and the gain was measured with an anechoic chamber.

  The center frequency was a center value of VSWR (Voltage Standing Wave Ratio) = 2, and the band was a value of VSWR = 2.

  Next, as shown in FIG. 3, in the state before the auxiliary conductor 17 is provided on the casing 11a facing the antenna 16, the electromagnetic field strength in the region 20 in the range 20 mm protruding from the outer periphery of the casing 11a is 2 mm pitch. Measurement was performed using an electromagnetic field intensity detection probe at a height of 2 mm from the body 11a.

  Note that a signal with a frequency of 1.57542 GHz is input to the antenna 16 through the feed line 18 using a spectrum analyzer. At each measurement point, the electromagnetic field strength in four or more directions was measured, and the maximum value was defined as the electromagnetic field strength at the measurement point. Further, the state of the wireless communication device at the time of measurement was measured with the external antenna 19 extended with the open state.

  Next, the auxiliary conductor 17 is applied to the main surface and a part of the side surface of the housing 11a with a conductive paint so as to cover part or all of the region of about 90% or less with respect to the maximum value of the electromagnetic field intensity distribution. Formed.

  Then, as before the auxiliary conductor 17 was formed, the antenna characteristics were measured with a network analyzer for the center frequency and band, and the gain was measured with an anechoic chamber.

  As a result, before the auxiliary conductor 17 was formed, the center frequency was 1.575 GHz, the band was 59 MHz, and the gain was −4.5 dBi.

  On the other hand, after the auxiliary conductor 17 was formed, characteristics with a center frequency of 1.575 GHz, a band of 63 MHz, and a gain of -2.2 dBi were obtained.

  As a result, it was found that the frequency band that can be communicated by widening the band was widened before forming the auxiliary conductor, the gain deterioration due to the variation in the antenna frequency during mass production was reduced, and the antenna gain was also improved. .

1 is a perspective view showing a first embodiment of a wireless communication apparatus of the present invention. It is the disassembled perspective view which decomposed | disassembled some housings | casings of the radio | wireless communication apparatus of FIG. (A), (b) is the front view and side view which show the range which measures the electromagnetic field intensity of the radio | wireless communication apparatus of this invention. (A) is a schematic diagram showing the electromagnetic field intensity distribution near the housing of the wireless communication apparatus before providing the auxiliary conductor, and (b) shows the electromagnetic field strength distribution near the housing after providing the auxiliary conductor. It is a schematic diagram. (A)-(c) is a figure which shows the preferable area | region which provides an auxiliary conductor. It is a perspective view which shows 2nd Embodiment of the radio | wireless communication apparatus of this invention. (A) is the disassembled perspective view which decomposed | disassembled the housing | casing containing the display part of the radio | wireless communication apparatus of FIG. 6, (b) was the disassembled perspective view which decomposed | disassembled the housing | casing which mounts an antenna. (A), (b) is the front view and side view which show the range which measures the electromagnetic field intensity of the radio | wireless communication apparatus of this invention. (A) is a schematic diagram showing the electromagnetic field intensity distribution near the housing of the wireless communication apparatus before providing the auxiliary conductor, and (b) shows the electromagnetic field strength distribution near the housing after providing the auxiliary conductor. It is a schematic diagram. It is a perspective view which shows the antenna in the conventional radio | wireless communication apparatus, and the technique of antenna characteristic improvement. It is a perspective view which shows the antenna in the conventional radio | wireless communication apparatus, and the technique of antenna characteristic improvement. It is a perspective view which shows the antenna in the conventional radio | wireless communication apparatus, and the technique of antenna characteristic improvement.

Explanation of symbols

10, 40: Wireless communication device 11, 12, 21, 22: Housing 13, 23: Hinge portion 14, 24: Display portion 15, 25, 147, 165: Substrate 16, 26, 146: Chip antenna 17, 27: Auxiliary conductors 18, 28: Feed line 19, 29: External antenna 20, 30: Electromagnetic field strength measurement region 50, 60: Ground conductor 122: Radiation electrode 123, 144: Substrate 125, 142, 163: Additional conductor 124: Feed Points 121, 141, 161: Antenna device 164: Shield case

Claims (6)

A circuit unit capable of wireless communication, a ground conductor for potential reference, and a substrate having a power supply line for connecting the circuit unit and the antenna, and connected to the power supply line on the substrate, forming an antenna conductor on the base A wireless communication apparatus in which an antenna is housed in a housing, wherein an auxiliary conductor independent of the antenna conductor is provided on a part of the inside of the housing. The wireless communication apparatus according to claim 1, wherein a ratio between the maximum value and the minimum value of the electromagnetic field intensity on a predetermined surface in the vicinity of the casing is 0.8 or more. The radio communication apparatus according to claim 1, wherein the auxiliary conductor is formed in a region excluding the outer peripheral surface side and the upper surface side of the antenna in the housing. The wireless communication apparatus according to claim 1, wherein the auxiliary conductor has a thickness equal to or greater than a skin depth of a desired frequency. The wireless communication apparatus according to claim 1, wherein the auxiliary conductor is connected to a ground conductor. A substrate having a circuit unit capable of wireless communication, a ground conductor for potential reference, and a power supply line for connecting the circuit unit and the antenna, and an antenna conductor connected to the power supply line on the substrate A method for improving antenna gain of a wireless communication device in which an antenna formed by housing is housed in a housing, and the electromagnetic field strength distribution near the housing is measured in advance and the maximum value of the obtained electromagnetic field strength is obtained. A method for improving antenna characteristics of a wireless communication device, comprising: an auxiliary conductor independent of the antenna conductor on the inside of a housing so as to cover a part or all of a region corresponding to less than 0.9.

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